Hot side of ballast resistor dead! Help!!

[jpilone]

So I have a reproduction harness on my 70 B body that converts it to the 72+ electronic ignition and 4 post ballast resistor. I've been using the hot side of the ballast resistor as the 12v switched source to trigger my holley sniper EFI. The hot side of the ballast where I've been sourcing it is now dead (and obviously the car doesn't start). I have no idea where to start. Is there a fusible link that feeds this? Or should I start by tracing wires at the ignition switch? I believe there is a wire from the ignition switch that feeds directly to that side of the ballast resistor.

Thank you in advance for any advice!!

 

[70chall440]

Does the car turn over? There is a fusible link in the system (wire coming off the starter relay) but without looking at a diagram I cannot remember if when broken cuts power off from the ignition (ign 1/2) side. I believe that the 2 wires in question are blue and brown

 

[Demonic]

That is generally ignition 1, and is usually fed by the ignition switch. That is rurn is fed via the ammeter from the fusible link. Check voltage at the ammeter, and firewall plug.

Jarred, is that you? It's Morgan, from the MML.

 

[jpilone]

Does the car turn over? There is a fusible link in the system (wire coming off the starter relay) but without looking at a diagram I cannot remember if when broken cuts power off from the ignition (ign 1/2) side. I believe that the 2 wires in question are blue and brown

The car cranks, but does not fire. If I run a jumper wire from the positive battery post to the hot side of the resistor, the car fires right up.

 

[jpilone]

That is generally ignition 1, and is usually fed by the ignition switch. That is rurn is fed via the ammeter from the fusible link. Check voltage at the ammeter, and firewall plug.

Jarred, is that you? It's Morgan, from the MML.

Yes sir!

I called M & H, who made the harness for Year One. They told me to check the blue/dk brown wires that feed that side of the resistor, at the bulkhead, and then the ignition switch. I've got some tracing of wires to do! I will go ahead and buy an ignition switch. They are cheap, and I have a feeling it'll be getting replaced (and I am NOT looking forward to changing it!!)

 

[Demonic]

https://mymopar.com/wiring/

 

[jpilone]

https://mymopar.com/wiring/

Thank you! I downloaded the harness diagram. Love this forum!

 

[Ron H]

You can test the the switch easy enough to rule it out before buying a new one. If it checks, I'd be inclined to put in another ballast to see what happens. I had issues when I put in a new wire harness finding it didn't like mating securely to my old BH. Finally said eff-it installing a new BH; but some of the damage had been done in my case. A poor connection at the ignition wire heated up enough to lose a tight spade connection there. Remove that wire from the harness and put in a new connecter that solved the ills. I keep a spare ballast and ECU in my trunk after a couple issues over the years.

 

[Demonic]

Check the tightness of the ammeter connections carefully, they tend to loosen over time. Watch the hot feeds through the firewall, same issue. I replaced my Packard connectors w the main harness in the dash. I have the M&H for when the car is restored. A set of good crimpers is a must.

 

[72RoadrunnerGTX]

Ignition switch voltages can be easily verified at its Molex connector at the bottom of the column. Dark blue is Ignition 1(+12v when running only), brown is ignition 2, ballast resistor by-pass,(+12v while cranking only). The ignition sense lead for the Sniper normally requires both the dark blue and brown to be connected together to provide +12v while cranking and running.

 

[jpilone]

So I came to conclusions that the 12v switched that I was sourcing for the sniper was overloading the circuit, as it's a direct line to the ignition switch. So without checking the switch at the connector (notate that statement), I used a test light at the bulkhead, and then tried it, it wouldn't crank, tried again, then it fired right up! Out of my long-term mopar knowledge, I went ahead and got an ignition switch locally. I picked it up at lunchtime today, planning on just plugging it in and moving the car in the parking garage at my work (I am the service manager at a Ford dealer). I crept under the dash, to find the ignition switch connector hanging on by a thread, and only inserted at a 30 degree angle. juuuust barely making contact. The shockwave of my hand made it completely disconnect.. I reconnected it, and put a ziptie around it for good measure..

Sometimes it's the simplest things...

However, I now plan to use my switched 12v source to trigger a relay, just to be safe and secure on the circuit...

 

[Ron H]

Interesting, the connector on the wire to the switch is bad or the wire crimp on it? Having worked on enough old rides, you can some times find all sorts of messed up or jury-rigged wiring from prior owner's or their buds installing stereos, speakers, etc. Includes having messed with the fuse block. Seems some aren't real cautious disrupting or damaging wires...

 

[jpilone]

Interesting, the connector on the wire to the switch is bad or the wire crimp on it? Having worked on enough old rides, you can some times find all sorts of messed up or jury-rigged wiring from prior owner's or their buds installing stereos, speakers, etc. Includes having messed with the fuse block. Seems some aren't real cautious disrupting or damaging wires...

I've owned the car 22 years. It's all reproduction wiring that has been put in during my ownership of the car. I caused this myself, because I remember pulling the connector when checking for a proper switched 12v source for the sniper EFI. It's all my fault! lol

 

[Demonic]

Glad you car didn't burn down.

I've posted this at times, but it bears repeating: Every old car needs a fire extinguisher with it.

 

[Ron H]

I've owned the car 22 years. It's all reproduction wiring that has been put in during my ownership of the car. I caused this myself, because I remember pulling the connector when checking for a proper switched 12v source for the sniper EFI. It's all my fault! lol

Lol, I won't start a long story about my eff ups. Demonic in post above, reminds me I should see if the old fire X I have actually would work.
Good luck.